error when run secondary_charp

LIB "finvar.lib";
ring R=0,(x,y,z),dp;
matrix A[3][3]=0,1,0,0,0,1,1,0,0;
matrix B(1..3);
B(1..3)=invariant_ring(A);
list L=primary_invariants(A);
matrix S,IS=secondary_charp(L[1..size(L)],1);

> matrix S,IS=secondary_charp(L[1..size(L)],1);
? `string`(ring_name) = `matrix` is not supported
? expected `string` = `string`
? error occurred in or before finvar.lib::secondary_charp line 5658: `atrix P; parameter matrix REY; parameter string ring_name; parameter list #; `
? wrong type declaration. type 'help string;'
? leaving finvar.lib::secondary_charp
skipping text from `;` error at token `)`

print(S);
print(IS);

secondary_charp is only valid in characteristic p (and has different arguments),
but your ring has characteristic 0.

which function can identify what the characteristic is?
i mean which function can find such as 0,1,2 these characteristics?

which function can be like this charp to run for characteristic 0 ?